[Elecraft] Appliance Operator gets gift

[Bill Coleman]

On 2/15/02 5:05 PM, George, W5YR at w5yr@att.net wrote:

>And Bill's mention of Class C reminds me of why we no longer use amplifiers
>- at least very seldom - that operate Class C: RFI . . .
>
>The older rigs that used frequency multiplication and Class C drivers and
>output stages had to be very carefully shielded and bypassed, etc. to
>operate around TV sets, etc. Perhaps your DX-40 already has had those steps
>taken - probably so.

To be fair, a design like the DX-40 ought to be fully compliant with all 
FCC regulations for purity of transmissions, even though it runs Class C.

Why? Because the pi network on the output has sufficient Q to supress 
unwanted energy. The high impedance of the vacuum tubes make this a 
simple process. (whereas the relatively low impedance of transistor 
output stages usually complicates it, and typically requires switched 
low-pass filters to clean up)

>So, when you get you "new" DX-40 running, you might want to do some extra
>checking on the TV situation.

And it will likely be OK.



Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901